M00.849
BillableArthritis due to other bacteria, unspecified hand
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is M00.849 an HCC code?
Yes. M00.849 maps to Bone/Joint/Muscle/Severe Soft Tissue Infections/Necrosis under the CMS-HCC V28 risk adjustment model (and Bone/Joint/Muscle Infections/Necrosis under V24).
HCC Category Mapping
RAF weights shown are the community, non-dual, aged base weights from the CMS risk adjustment model file. Actual per-patient RAF contribution depends on member segment, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains in use during the transition and for historical data.
MEAT Criteria for M00.849
For M00.849to count as a valid HCC diagnosis in a given encounter, the provider's documentation must show MEAT: Monitor, Evaluate, Assess, or Treat. A diagnosis from a prior year does not carry forward automatically — it has to be re-documented and supported each calendar year.
- MMonitor: signs, symptoms, disease progression, or lab trending documented in the note
- EEvaluate: test results, medication response, or physical findings reviewed by the provider
- AAssess: explicit mention in the assessment or plan with acknowledgment of status
- TTreat: medication, referral, procedure, therapy, or counseling tied to the diagnosis
Only one of M/E/A/T is required to support the code, but the documentation must be specific enough to show that the provider actually addressed M00.849 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
M00.849 is the ICD-10-CM diagnosis code for arthritis due to other bacteria, unspecified hand. Infection and inflammation of the hand joints caused by bacteria other than the common ones typically associated with arthritis, when the specific hand is not identified. M00.849 sits in the ICD-10-CM chapter for diseases of the musculoskeletal system and connective tissue (m00-m99), within the section covering infectious arthropathies (m00-m02).
Under the CMS-HCC V28 risk adjustment model, M00.849 maps to Bone/Joint/Muscle/Severe Soft Tissue Infections/Necrosis (HCC 92) with a community, non-dual, aged base RAF weight of 0.479. Under the older CMS-HCC V24 model, M00.849 maps to Bone/Joint/Muscle Infections/Necrosis (HCC 39) with a community, non-dual, aged base RAF weight of 0.401. V28 is the CMS-HCC risk adjustment model that reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition.
Use this code only when laterality is not specified in documentation. Because M00.849 maps to a payment HCC, the provider's documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's Medicare Advantage risk adjustment score. When documentation is ambiguous, coders should issue a provider query rather than assume the highest-specificity variant.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for M00.849 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Use this code only when laterality is not specified in documentation
- •Query the provider if the affected hand can be determined from clinical context
Clinical Significance
Bacterial arthritis of unspecified hand indicates a serious infection of the complex hand joints that are essential for daily function, though documentation lacks laterality. This condition requires immediate treatment to prevent permanent loss of hand function and dexterity.
Documentation Requirements
- ✓Evidence of 'other bacteria' causing hand joint infection
- ✓Documentation of hand joint involvement without laterality
- ✓Bacterial culture or microbiological confirmation
- ✓Signs and symptoms of infectious arthritis
- ✓Treatment with appropriate antibiotics
- ✓Assessment of hand function and range of motion
- ✓Laboratory markers of infection
- ✓Clarification of laterality for future encounters
Commonly Confused Codes
- •M00.841/M00.842 — Same condition with specific laterality
- •M00049 — Streptococcal arthritis of unspecified hand (different organism)
- •M00019 — Staphylococcal arthritis of unspecified hand (specific bacteria)
- •M06.849 — Other rheumatoid arthritis of unspecified hand (autoimmune)
- •L03.119 — Cellulitis of unspecified hand (soft tissue)